linux/drivers/vhost/net.c
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   1/* Copyright (C) 2009 Red Hat, Inc.
   2 * Author: Michael S. Tsirkin <mst@redhat.com>
   3 *
   4 * This work is licensed under the terms of the GNU GPL, version 2.
   5 *
   6 * virtio-net server in host kernel.
   7 */
   8
   9#include <linux/compat.h>
  10#include <linux/eventfd.h>
  11#include <linux/vhost.h>
  12#include <linux/virtio_net.h>
  13#include <linux/miscdevice.h>
  14#include <linux/module.h>
  15#include <linux/moduleparam.h>
  16#include <linux/mutex.h>
  17#include <linux/workqueue.h>
  18#include <linux/file.h>
  19#include <linux/slab.h>
  20
  21#include <linux/net.h>
  22#include <linux/if_packet.h>
  23#include <linux/if_arp.h>
  24#include <linux/if_tun.h>
  25#include <linux/if_macvlan.h>
  26#include <linux/if_vlan.h>
  27
  28#include <net/sock.h>
  29
  30#include "vhost.h"
  31
  32static int experimental_zcopytx = 1;
  33module_param(experimental_zcopytx, int, 0444);
  34MODULE_PARM_DESC(experimental_zcopytx, "Enable Zero Copy TX;"
  35                                       " 1 -Enable; 0 - Disable");
  36
  37/* Max number of bytes transferred before requeueing the job.
  38 * Using this limit prevents one virtqueue from starving others. */
  39#define VHOST_NET_WEIGHT 0x80000
  40
  41/* MAX number of TX used buffers for outstanding zerocopy */
  42#define VHOST_MAX_PEND 128
  43#define VHOST_GOODCOPY_LEN 256
  44
  45/*
  46 * For transmit, used buffer len is unused; we override it to track buffer
  47 * status internally; used for zerocopy tx only.
  48 */
  49/* Lower device DMA failed */
  50#define VHOST_DMA_FAILED_LEN    3
  51/* Lower device DMA done */
  52#define VHOST_DMA_DONE_LEN      2
  53/* Lower device DMA in progress */
  54#define VHOST_DMA_IN_PROGRESS   1
  55/* Buffer unused */
  56#define VHOST_DMA_CLEAR_LEN     0
  57
  58#define VHOST_DMA_IS_DONE(len) ((len) >= VHOST_DMA_DONE_LEN)
  59
  60enum {
  61        VHOST_NET_FEATURES = VHOST_FEATURES |
  62                         (1ULL << VHOST_NET_F_VIRTIO_NET_HDR) |
  63                         (1ULL << VIRTIO_NET_F_MRG_RXBUF),
  64};
  65
  66enum {
  67        VHOST_NET_VQ_RX = 0,
  68        VHOST_NET_VQ_TX = 1,
  69        VHOST_NET_VQ_MAX = 2,
  70};
  71
  72struct vhost_net_ubuf_ref {
  73        struct kref kref;
  74        wait_queue_head_t wait;
  75        struct vhost_virtqueue *vq;
  76};
  77
  78struct vhost_net_virtqueue {
  79        struct vhost_virtqueue vq;
  80        /* hdr is used to store the virtio header.
  81         * Since each iovec has >= 1 byte length, we never need more than
  82         * header length entries to store the header. */
  83        struct iovec hdr[sizeof(struct virtio_net_hdr_mrg_rxbuf)];
  84        size_t vhost_hlen;
  85        size_t sock_hlen;
  86        /* vhost zerocopy support fields below: */
  87        /* last used idx for outstanding DMA zerocopy buffers */
  88        int upend_idx;
  89        /* first used idx for DMA done zerocopy buffers */
  90        int done_idx;
  91        /* an array of userspace buffers info */
  92        struct ubuf_info *ubuf_info;
  93        /* Reference counting for outstanding ubufs.
  94         * Protected by vq mutex. Writers must also take device mutex. */
  95        struct vhost_net_ubuf_ref *ubufs;
  96};
  97
  98struct vhost_net {
  99        struct vhost_dev dev;
 100        struct vhost_net_virtqueue vqs[VHOST_NET_VQ_MAX];
 101        struct vhost_poll poll[VHOST_NET_VQ_MAX];
 102        /* Number of TX recently submitted.
 103         * Protected by tx vq lock. */
 104        unsigned tx_packets;
 105        /* Number of times zerocopy TX recently failed.
 106         * Protected by tx vq lock. */
 107        unsigned tx_zcopy_err;
 108        /* Flush in progress. Protected by tx vq lock. */
 109        bool tx_flush;
 110};
 111
 112static unsigned vhost_net_zcopy_mask __read_mostly;
 113
 114static void vhost_net_enable_zcopy(int vq)
 115{
 116        vhost_net_zcopy_mask |= 0x1 << vq;
 117}
 118
 119static void vhost_net_zerocopy_done_signal(struct kref *kref)
 120{
 121        struct vhost_net_ubuf_ref *ubufs;
 122
 123        ubufs = container_of(kref, struct vhost_net_ubuf_ref, kref);
 124        wake_up(&ubufs->wait);
 125}
 126
 127static struct vhost_net_ubuf_ref *
 128vhost_net_ubuf_alloc(struct vhost_virtqueue *vq, bool zcopy)
 129{
 130        struct vhost_net_ubuf_ref *ubufs;
 131        /* No zero copy backend? Nothing to count. */
 132        if (!zcopy)
 133                return NULL;
 134        ubufs = kmalloc(sizeof(*ubufs), GFP_KERNEL);
 135        if (!ubufs)
 136                return ERR_PTR(-ENOMEM);
 137        kref_init(&ubufs->kref);
 138        init_waitqueue_head(&ubufs->wait);
 139        ubufs->vq = vq;
 140        return ubufs;
 141}
 142
 143static void vhost_net_ubuf_put(struct vhost_net_ubuf_ref *ubufs)
 144{
 145        kref_put(&ubufs->kref, vhost_net_zerocopy_done_signal);
 146}
 147
 148static void vhost_net_ubuf_put_and_wait(struct vhost_net_ubuf_ref *ubufs)
 149{
 150        kref_put(&ubufs->kref, vhost_net_zerocopy_done_signal);
 151        wait_event(ubufs->wait, !atomic_read(&ubufs->kref.refcount));
 152}
 153
 154static void vhost_net_ubuf_put_wait_and_free(struct vhost_net_ubuf_ref *ubufs)
 155{
 156        vhost_net_ubuf_put_and_wait(ubufs);
 157        kfree(ubufs);
 158}
 159
 160static void vhost_net_clear_ubuf_info(struct vhost_net *n)
 161{
 162        int i;
 163
 164        for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 165                kfree(n->vqs[i].ubuf_info);
 166                n->vqs[i].ubuf_info = NULL;
 167        }
 168}
 169
 170static int vhost_net_set_ubuf_info(struct vhost_net *n)
 171{
 172        bool zcopy;
 173        int i;
 174
 175        for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
 176                zcopy = vhost_net_zcopy_mask & (0x1 << i);
 177                if (!zcopy)
 178                        continue;
 179                n->vqs[i].ubuf_info = kmalloc(sizeof(*n->vqs[i].ubuf_info) *
 180                                              UIO_MAXIOV, GFP_KERNEL);
 181                if  (!n->vqs[i].ubuf_info)
 182                        goto err;
 183        }
 184        return 0;
 185
 186err:
 187        vhost_net_clear_ubuf_info(n);
 188        return -ENOMEM;
 189}
 190
 191static void vhost_net_vq_reset(struct vhost_net *n)
 192{
 193        int i;
 194
 195        vhost_net_clear_ubuf_info(n);
 196
 197        for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 198                n->vqs[i].done_idx = 0;
 199                n->vqs[i].upend_idx = 0;
 200                n->vqs[i].ubufs = NULL;
 201                n->vqs[i].vhost_hlen = 0;
 202                n->vqs[i].sock_hlen = 0;
 203        }
 204
 205}
 206
 207static void vhost_net_tx_packet(struct vhost_net *net)
 208{
 209        ++net->tx_packets;
 210        if (net->tx_packets < 1024)
 211                return;
 212        net->tx_packets = 0;
 213        net->tx_zcopy_err = 0;
 214}
 215
 216static void vhost_net_tx_err(struct vhost_net *net)
 217{
 218        ++net->tx_zcopy_err;
 219}
 220
 221static bool vhost_net_tx_select_zcopy(struct vhost_net *net)
 222{
 223        /* TX flush waits for outstanding DMAs to be done.
 224         * Don't start new DMAs.
 225         */
 226        return !net->tx_flush &&
 227                net->tx_packets / 64 >= net->tx_zcopy_err;
 228}
 229
 230static bool vhost_sock_zcopy(struct socket *sock)
 231{
 232        return unlikely(experimental_zcopytx) &&
 233                sock_flag(sock->sk, SOCK_ZEROCOPY);
 234}
 235
 236/* Pop first len bytes from iovec. Return number of segments used. */
 237static int move_iovec_hdr(struct iovec *from, struct iovec *to,
 238                          size_t len, int iov_count)
 239{
 240        int seg = 0;
 241        size_t size;
 242
 243        while (len && seg < iov_count) {
 244                size = min(from->iov_len, len);
 245                to->iov_base = from->iov_base;
 246                to->iov_len = size;
 247                from->iov_len -= size;
 248                from->iov_base += size;
 249                len -= size;
 250                ++from;
 251                ++to;
 252                ++seg;
 253        }
 254        return seg;
 255}
 256/* Copy iovec entries for len bytes from iovec. */
 257static void copy_iovec_hdr(const struct iovec *from, struct iovec *to,
 258                           size_t len, int iovcount)
 259{
 260        int seg = 0;
 261        size_t size;
 262
 263        while (len && seg < iovcount) {
 264                size = min(from->iov_len, len);
 265                to->iov_base = from->iov_base;
 266                to->iov_len = size;
 267                len -= size;
 268                ++from;
 269                ++to;
 270                ++seg;
 271        }
 272}
 273
 274/* In case of DMA done not in order in lower device driver for some reason.
 275 * upend_idx is used to track end of used idx, done_idx is used to track head
 276 * of used idx. Once lower device DMA done contiguously, we will signal KVM
 277 * guest used idx.
 278 */
 279static int vhost_zerocopy_signal_used(struct vhost_net *net,
 280                                      struct vhost_virtqueue *vq)
 281{
 282        struct vhost_net_virtqueue *nvq =
 283                container_of(vq, struct vhost_net_virtqueue, vq);
 284        int i;
 285        int j = 0;
 286
 287        for (i = nvq->done_idx; i != nvq->upend_idx; i = (i + 1) % UIO_MAXIOV) {
 288                if (vq->heads[i].len == VHOST_DMA_FAILED_LEN)
 289                        vhost_net_tx_err(net);
 290                if (VHOST_DMA_IS_DONE(vq->heads[i].len)) {
 291                        vq->heads[i].len = VHOST_DMA_CLEAR_LEN;
 292                        vhost_add_used_and_signal(vq->dev, vq,
 293                                                  vq->heads[i].id, 0);
 294                        ++j;
 295                } else
 296                        break;
 297        }
 298        if (j)
 299                nvq->done_idx = i;
 300        return j;
 301}
 302
 303static void vhost_zerocopy_callback(struct ubuf_info *ubuf, bool success)
 304{
 305        struct vhost_net_ubuf_ref *ubufs = ubuf->ctx;
 306        struct vhost_virtqueue *vq = ubufs->vq;
 307        int cnt = atomic_read(&ubufs->kref.refcount);
 308
 309        /*
 310         * Trigger polling thread if guest stopped submitting new buffers:
 311         * in this case, the refcount after decrement will eventually reach 1
 312         * so here it is 2.
 313         * We also trigger polling periodically after each 16 packets
 314         * (the value 16 here is more or less arbitrary, it's tuned to trigger
 315         * less than 10% of times).
 316         */
 317        if (cnt <= 2 || !(cnt % 16))
 318                vhost_poll_queue(&vq->poll);
 319        /* set len to mark this desc buffers done DMA */
 320        vq->heads[ubuf->desc].len = success ?
 321                VHOST_DMA_DONE_LEN : VHOST_DMA_FAILED_LEN;
 322        vhost_net_ubuf_put(ubufs);
 323}
 324
 325/* Expects to be always run from workqueue - which acts as
 326 * read-size critical section for our kind of RCU. */
 327static void handle_tx(struct vhost_net *net)
 328{
 329        struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_TX];
 330        struct vhost_virtqueue *vq = &nvq->vq;
 331        unsigned out, in, s;
 332        int head;
 333        struct msghdr msg = {
 334                .msg_name = NULL,
 335                .msg_namelen = 0,
 336                .msg_control = NULL,
 337                .msg_controllen = 0,
 338                .msg_iov = vq->iov,
 339                .msg_flags = MSG_DONTWAIT,
 340        };
 341        size_t len, total_len = 0;
 342        int err;
 343        size_t hdr_size;
 344        struct socket *sock;
 345        struct vhost_net_ubuf_ref *uninitialized_var(ubufs);
 346        bool zcopy, zcopy_used;
 347
 348        mutex_lock(&vq->mutex);
 349        sock = vq->private_data;
 350        if (!sock)
 351                goto out;
 352
 353        vhost_disable_notify(&net->dev, vq);
 354
 355        hdr_size = nvq->vhost_hlen;
 356        zcopy = nvq->ubufs;
 357
 358        for (;;) {
 359                /* Release DMAs done buffers first */
 360                if (zcopy)
 361                        vhost_zerocopy_signal_used(net, vq);
 362
 363                head = vhost_get_vq_desc(&net->dev, vq, vq->iov,
 364                                         ARRAY_SIZE(vq->iov),
 365                                         &out, &in,
 366                                         NULL, NULL);
 367                /* On error, stop handling until the next kick. */
 368                if (unlikely(head < 0))
 369                        break;
 370                /* Nothing new?  Wait for eventfd to tell us they refilled. */
 371                if (head == vq->num) {
 372                        int num_pends;
 373
 374                        /* If more outstanding DMAs, queue the work.
 375                         * Handle upend_idx wrap around
 376                         */
 377                        num_pends = likely(nvq->upend_idx >= nvq->done_idx) ?
 378                                    (nvq->upend_idx - nvq->done_idx) :
 379                                    (nvq->upend_idx + UIO_MAXIOV -
 380                                     nvq->done_idx);
 381                        if (unlikely(num_pends > VHOST_MAX_PEND))
 382                                break;
 383                        if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 384                                vhost_disable_notify(&net->dev, vq);
 385                                continue;
 386                        }
 387                        break;
 388                }
 389                if (in) {
 390                        vq_err(vq, "Unexpected descriptor format for TX: "
 391                               "out %d, int %d\n", out, in);
 392                        break;
 393                }
 394                /* Skip header. TODO: support TSO. */
 395                s = move_iovec_hdr(vq->iov, nvq->hdr, hdr_size, out);
 396                msg.msg_iovlen = out;
 397                len = iov_length(vq->iov, out);
 398                /* Sanity check */
 399                if (!len) {
 400                        vq_err(vq, "Unexpected header len for TX: "
 401                               "%zd expected %zd\n",
 402                               iov_length(nvq->hdr, s), hdr_size);
 403                        break;
 404                }
 405                zcopy_used = zcopy && (len >= VHOST_GOODCOPY_LEN ||
 406                                       nvq->upend_idx != nvq->done_idx);
 407
 408                /* use msg_control to pass vhost zerocopy ubuf info to skb */
 409                if (zcopy_used) {
 410                        vq->heads[nvq->upend_idx].id = head;
 411                        if (!vhost_net_tx_select_zcopy(net) ||
 412                            len < VHOST_GOODCOPY_LEN) {
 413                                /* copy don't need to wait for DMA done */
 414                                vq->heads[nvq->upend_idx].len =
 415                                                        VHOST_DMA_DONE_LEN;
 416                                msg.msg_control = NULL;
 417                                msg.msg_controllen = 0;
 418                                ubufs = NULL;
 419                        } else {
 420                                struct ubuf_info *ubuf;
 421                                ubuf = nvq->ubuf_info + nvq->upend_idx;
 422
 423                                vq->heads[nvq->upend_idx].len =
 424                                        VHOST_DMA_IN_PROGRESS;
 425                                ubuf->callback = vhost_zerocopy_callback;
 426                                ubuf->ctx = nvq->ubufs;
 427                                ubuf->desc = nvq->upend_idx;
 428                                msg.msg_control = ubuf;
 429                                msg.msg_controllen = sizeof(ubuf);
 430                                ubufs = nvq->ubufs;
 431                                kref_get(&ubufs->kref);
 432                        }
 433                        nvq->upend_idx = (nvq->upend_idx + 1) % UIO_MAXIOV;
 434                } else
 435                        msg.msg_control = NULL;
 436                /* TODO: Check specific error and bomb out unless ENOBUFS? */
 437                err = sock->ops->sendmsg(NULL, sock, &msg, len);
 438                if (unlikely(err < 0)) {
 439                        if (zcopy_used) {
 440                                if (ubufs)
 441                                        vhost_net_ubuf_put(ubufs);
 442                                nvq->upend_idx = ((unsigned)nvq->upend_idx - 1)
 443                                        % UIO_MAXIOV;
 444                        }
 445                        vhost_discard_vq_desc(vq, 1);
 446                        break;
 447                }
 448                if (err != len)
 449                        pr_debug("Truncated TX packet: "
 450                                 " len %d != %zd\n", err, len);
 451                if (!zcopy_used)
 452                        vhost_add_used_and_signal(&net->dev, vq, head, 0);
 453                else
 454                        vhost_zerocopy_signal_used(net, vq);
 455                total_len += len;
 456                vhost_net_tx_packet(net);
 457                if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 458                        vhost_poll_queue(&vq->poll);
 459                        break;
 460                }
 461        }
 462out:
 463        mutex_unlock(&vq->mutex);
 464}
 465
 466static int peek_head_len(struct sock *sk)
 467{
 468        struct sk_buff *head;
 469        int len = 0;
 470        unsigned long flags;
 471
 472        spin_lock_irqsave(&sk->sk_receive_queue.lock, flags);
 473        head = skb_peek(&sk->sk_receive_queue);
 474        if (likely(head)) {
 475                len = head->len;
 476                if (vlan_tx_tag_present(head))
 477                        len += VLAN_HLEN;
 478        }
 479
 480        spin_unlock_irqrestore(&sk->sk_receive_queue.lock, flags);
 481        return len;
 482}
 483
 484/* This is a multi-buffer version of vhost_get_desc, that works if
 485 *      vq has read descriptors only.
 486 * @vq          - the relevant virtqueue
 487 * @datalen     - data length we'll be reading
 488 * @iovcount    - returned count of io vectors we fill
 489 * @log         - vhost log
 490 * @log_num     - log offset
 491 * @quota       - headcount quota, 1 for big buffer
 492 *      returns number of buffer heads allocated, negative on error
 493 */
 494static int get_rx_bufs(struct vhost_virtqueue *vq,
 495                       struct vring_used_elem *heads,
 496                       int datalen,
 497                       unsigned *iovcount,
 498                       struct vhost_log *log,
 499                       unsigned *log_num,
 500                       unsigned int quota)
 501{
 502        unsigned int out, in;
 503        int seg = 0;
 504        int headcount = 0;
 505        unsigned d;
 506        int r, nlogs = 0;
 507
 508        while (datalen > 0 && headcount < quota) {
 509                if (unlikely(seg >= UIO_MAXIOV)) {
 510                        r = -ENOBUFS;
 511                        goto err;
 512                }
 513                d = vhost_get_vq_desc(vq->dev, vq, vq->iov + seg,
 514                                      ARRAY_SIZE(vq->iov) - seg, &out,
 515                                      &in, log, log_num);
 516                if (d == vq->num) {
 517                        r = 0;
 518                        goto err;
 519                }
 520                if (unlikely(out || in <= 0)) {
 521                        vq_err(vq, "unexpected descriptor format for RX: "
 522                                "out %d, in %d\n", out, in);
 523                        r = -EINVAL;
 524                        goto err;
 525                }
 526                if (unlikely(log)) {
 527                        nlogs += *log_num;
 528                        log += *log_num;
 529                }
 530                heads[headcount].id = d;
 531                heads[headcount].len = iov_length(vq->iov + seg, in);
 532                datalen -= heads[headcount].len;
 533                ++headcount;
 534                seg += in;
 535        }
 536        heads[headcount - 1].len += datalen;
 537        *iovcount = seg;
 538        if (unlikely(log))
 539                *log_num = nlogs;
 540        return headcount;
 541err:
 542        vhost_discard_vq_desc(vq, headcount);
 543        return r;
 544}
 545
 546/* Expects to be always run from workqueue - which acts as
 547 * read-size critical section for our kind of RCU. */
 548static void handle_rx(struct vhost_net *net)
 549{
 550        struct vhost_net_virtqueue *nvq = &net->vqs[VHOST_NET_VQ_RX];
 551        struct vhost_virtqueue *vq = &nvq->vq;
 552        unsigned uninitialized_var(in), log;
 553        struct vhost_log *vq_log;
 554        struct msghdr msg = {
 555                .msg_name = NULL,
 556                .msg_namelen = 0,
 557                .msg_control = NULL, /* FIXME: get and handle RX aux data. */
 558                .msg_controllen = 0,
 559                .msg_iov = vq->iov,
 560                .msg_flags = MSG_DONTWAIT,
 561        };
 562        struct virtio_net_hdr_mrg_rxbuf hdr = {
 563                .hdr.flags = 0,
 564                .hdr.gso_type = VIRTIO_NET_HDR_GSO_NONE
 565        };
 566        size_t total_len = 0;
 567        int err, mergeable;
 568        s16 headcount;
 569        size_t vhost_hlen, sock_hlen;
 570        size_t vhost_len, sock_len;
 571        struct socket *sock;
 572
 573        mutex_lock(&vq->mutex);
 574        sock = vq->private_data;
 575        if (!sock)
 576                goto out;
 577        vhost_disable_notify(&net->dev, vq);
 578
 579        vhost_hlen = nvq->vhost_hlen;
 580        sock_hlen = nvq->sock_hlen;
 581
 582        vq_log = unlikely(vhost_has_feature(&net->dev, VHOST_F_LOG_ALL)) ?
 583                vq->log : NULL;
 584        mergeable = vhost_has_feature(&net->dev, VIRTIO_NET_F_MRG_RXBUF);
 585
 586        while ((sock_len = peek_head_len(sock->sk))) {
 587                sock_len += sock_hlen;
 588                vhost_len = sock_len + vhost_hlen;
 589                headcount = get_rx_bufs(vq, vq->heads, vhost_len,
 590                                        &in, vq_log, &log,
 591                                        likely(mergeable) ? UIO_MAXIOV : 1);
 592                /* On error, stop handling until the next kick. */
 593                if (unlikely(headcount < 0))
 594                        break;
 595                /* OK, now we need to know about added descriptors. */
 596                if (!headcount) {
 597                        if (unlikely(vhost_enable_notify(&net->dev, vq))) {
 598                                /* They have slipped one in as we were
 599                                 * doing that: check again. */
 600                                vhost_disable_notify(&net->dev, vq);
 601                                continue;
 602                        }
 603                        /* Nothing new?  Wait for eventfd to tell us
 604                         * they refilled. */
 605                        break;
 606                }
 607                /* We don't need to be notified again. */
 608                if (unlikely((vhost_hlen)))
 609                        /* Skip header. TODO: support TSO. */
 610                        move_iovec_hdr(vq->iov, nvq->hdr, vhost_hlen, in);
 611                else
 612                        /* Copy the header for use in VIRTIO_NET_F_MRG_RXBUF:
 613                         * needed because recvmsg can modify msg_iov. */
 614                        copy_iovec_hdr(vq->iov, nvq->hdr, sock_hlen, in);
 615                msg.msg_iovlen = in;
 616                err = sock->ops->recvmsg(NULL, sock, &msg,
 617                                         sock_len, MSG_DONTWAIT | MSG_TRUNC);
 618                /* Userspace might have consumed the packet meanwhile:
 619                 * it's not supposed to do this usually, but might be hard
 620                 * to prevent. Discard data we got (if any) and keep going. */
 621                if (unlikely(err != sock_len)) {
 622                        pr_debug("Discarded rx packet: "
 623                                 " len %d, expected %zd\n", err, sock_len);
 624                        vhost_discard_vq_desc(vq, headcount);
 625                        continue;
 626                }
 627                if (unlikely(vhost_hlen) &&
 628                    memcpy_toiovecend(nvq->hdr, (unsigned char *)&hdr, 0,
 629                                      vhost_hlen)) {
 630                        vq_err(vq, "Unable to write vnet_hdr at addr %p\n",
 631                               vq->iov->iov_base);
 632                        break;
 633                }
 634                /* TODO: Should check and handle checksum. */
 635                if (likely(mergeable) &&
 636                    memcpy_toiovecend(nvq->hdr, (unsigned char *)&headcount,
 637                                      offsetof(typeof(hdr), num_buffers),
 638                                      sizeof hdr.num_buffers)) {
 639                        vq_err(vq, "Failed num_buffers write");
 640                        vhost_discard_vq_desc(vq, headcount);
 641                        break;
 642                }
 643                vhost_add_used_and_signal_n(&net->dev, vq, vq->heads,
 644                                            headcount);
 645                if (unlikely(vq_log))
 646                        vhost_log_write(vq, vq_log, log, vhost_len);
 647                total_len += vhost_len;
 648                if (unlikely(total_len >= VHOST_NET_WEIGHT)) {
 649                        vhost_poll_queue(&vq->poll);
 650                        break;
 651                }
 652        }
 653out:
 654        mutex_unlock(&vq->mutex);
 655}
 656
 657static void handle_tx_kick(struct vhost_work *work)
 658{
 659        struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 660                                                  poll.work);
 661        struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 662
 663        handle_tx(net);
 664}
 665
 666static void handle_rx_kick(struct vhost_work *work)
 667{
 668        struct vhost_virtqueue *vq = container_of(work, struct vhost_virtqueue,
 669                                                  poll.work);
 670        struct vhost_net *net = container_of(vq->dev, struct vhost_net, dev);
 671
 672        handle_rx(net);
 673}
 674
 675static void handle_tx_net(struct vhost_work *work)
 676{
 677        struct vhost_net *net = container_of(work, struct vhost_net,
 678                                             poll[VHOST_NET_VQ_TX].work);
 679        handle_tx(net);
 680}
 681
 682static void handle_rx_net(struct vhost_work *work)
 683{
 684        struct vhost_net *net = container_of(work, struct vhost_net,
 685                                             poll[VHOST_NET_VQ_RX].work);
 686        handle_rx(net);
 687}
 688
 689static int vhost_net_open(struct inode *inode, struct file *f)
 690{
 691        struct vhost_net *n = kmalloc(sizeof *n, GFP_KERNEL);
 692        struct vhost_dev *dev;
 693        struct vhost_virtqueue **vqs;
 694        int r, i;
 695
 696        if (!n)
 697                return -ENOMEM;
 698        vqs = kmalloc(VHOST_NET_VQ_MAX * sizeof(*vqs), GFP_KERNEL);
 699        if (!vqs) {
 700                kfree(n);
 701                return -ENOMEM;
 702        }
 703
 704        dev = &n->dev;
 705        vqs[VHOST_NET_VQ_TX] = &n->vqs[VHOST_NET_VQ_TX].vq;
 706        vqs[VHOST_NET_VQ_RX] = &n->vqs[VHOST_NET_VQ_RX].vq;
 707        n->vqs[VHOST_NET_VQ_TX].vq.handle_kick = handle_tx_kick;
 708        n->vqs[VHOST_NET_VQ_RX].vq.handle_kick = handle_rx_kick;
 709        for (i = 0; i < VHOST_NET_VQ_MAX; i++) {
 710                n->vqs[i].ubufs = NULL;
 711                n->vqs[i].ubuf_info = NULL;
 712                n->vqs[i].upend_idx = 0;
 713                n->vqs[i].done_idx = 0;
 714                n->vqs[i].vhost_hlen = 0;
 715                n->vqs[i].sock_hlen = 0;
 716        }
 717        r = vhost_dev_init(dev, vqs, VHOST_NET_VQ_MAX);
 718        if (r < 0) {
 719                kfree(n);
 720                kfree(vqs);
 721                return r;
 722        }
 723
 724        vhost_poll_init(n->poll + VHOST_NET_VQ_TX, handle_tx_net, POLLOUT, dev);
 725        vhost_poll_init(n->poll + VHOST_NET_VQ_RX, handle_rx_net, POLLIN, dev);
 726
 727        f->private_data = n;
 728
 729        return 0;
 730}
 731
 732static void vhost_net_disable_vq(struct vhost_net *n,
 733                                 struct vhost_virtqueue *vq)
 734{
 735        struct vhost_net_virtqueue *nvq =
 736                container_of(vq, struct vhost_net_virtqueue, vq);
 737        struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 738        if (!vq->private_data)
 739                return;
 740        vhost_poll_stop(poll);
 741}
 742
 743static int vhost_net_enable_vq(struct vhost_net *n,
 744                                struct vhost_virtqueue *vq)
 745{
 746        struct vhost_net_virtqueue *nvq =
 747                container_of(vq, struct vhost_net_virtqueue, vq);
 748        struct vhost_poll *poll = n->poll + (nvq - n->vqs);
 749        struct socket *sock;
 750
 751        sock = vq->private_data;
 752        if (!sock)
 753                return 0;
 754
 755        return vhost_poll_start(poll, sock->file);
 756}
 757
 758static struct socket *vhost_net_stop_vq(struct vhost_net *n,
 759                                        struct vhost_virtqueue *vq)
 760{
 761        struct socket *sock;
 762
 763        mutex_lock(&vq->mutex);
 764        sock = vq->private_data;
 765        vhost_net_disable_vq(n, vq);
 766        vq->private_data = NULL;
 767        mutex_unlock(&vq->mutex);
 768        return sock;
 769}
 770
 771static void vhost_net_stop(struct vhost_net *n, struct socket **tx_sock,
 772                           struct socket **rx_sock)
 773{
 774        *tx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_TX].vq);
 775        *rx_sock = vhost_net_stop_vq(n, &n->vqs[VHOST_NET_VQ_RX].vq);
 776}
 777
 778static void vhost_net_flush_vq(struct vhost_net *n, int index)
 779{
 780        vhost_poll_flush(n->poll + index);
 781        vhost_poll_flush(&n->vqs[index].vq.poll);
 782}
 783
 784static void vhost_net_flush(struct vhost_net *n)
 785{
 786        vhost_net_flush_vq(n, VHOST_NET_VQ_TX);
 787        vhost_net_flush_vq(n, VHOST_NET_VQ_RX);
 788        if (n->vqs[VHOST_NET_VQ_TX].ubufs) {
 789                mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 790                n->tx_flush = true;
 791                mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 792                /* Wait for all lower device DMAs done. */
 793                vhost_net_ubuf_put_and_wait(n->vqs[VHOST_NET_VQ_TX].ubufs);
 794                mutex_lock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 795                n->tx_flush = false;
 796                kref_init(&n->vqs[VHOST_NET_VQ_TX].ubufs->kref);
 797                mutex_unlock(&n->vqs[VHOST_NET_VQ_TX].vq.mutex);
 798        }
 799}
 800
 801static int vhost_net_release(struct inode *inode, struct file *f)
 802{
 803        struct vhost_net *n = f->private_data;
 804        struct socket *tx_sock;
 805        struct socket *rx_sock;
 806
 807        vhost_net_stop(n, &tx_sock, &rx_sock);
 808        vhost_net_flush(n);
 809        vhost_dev_stop(&n->dev);
 810        vhost_dev_cleanup(&n->dev, false);
 811        vhost_net_vq_reset(n);
 812        if (tx_sock)
 813                fput(tx_sock->file);
 814        if (rx_sock)
 815                fput(rx_sock->file);
 816        /* We do an extra flush before freeing memory,
 817         * since jobs can re-queue themselves. */
 818        vhost_net_flush(n);
 819        kfree(n->dev.vqs);
 820        kfree(n);
 821        return 0;
 822}
 823
 824static struct socket *get_raw_socket(int fd)
 825{
 826        struct {
 827                struct sockaddr_ll sa;
 828                char  buf[MAX_ADDR_LEN];
 829        } uaddr;
 830        int uaddr_len = sizeof uaddr, r;
 831        struct socket *sock = sockfd_lookup(fd, &r);
 832
 833        if (!sock)
 834                return ERR_PTR(-ENOTSOCK);
 835
 836        /* Parameter checking */
 837        if (sock->sk->sk_type != SOCK_RAW) {
 838                r = -ESOCKTNOSUPPORT;
 839                goto err;
 840        }
 841
 842        r = sock->ops->getname(sock, (struct sockaddr *)&uaddr.sa,
 843                               &uaddr_len, 0);
 844        if (r)
 845                goto err;
 846
 847        if (uaddr.sa.sll_family != AF_PACKET) {
 848                r = -EPFNOSUPPORT;
 849                goto err;
 850        }
 851        return sock;
 852err:
 853        fput(sock->file);
 854        return ERR_PTR(r);
 855}
 856
 857static struct socket *get_tap_socket(int fd)
 858{
 859        struct file *file = fget(fd);
 860        struct socket *sock;
 861
 862        if (!file)
 863                return ERR_PTR(-EBADF);
 864        sock = tun_get_socket(file);
 865        if (!IS_ERR(sock))
 866                return sock;
 867        sock = macvtap_get_socket(file);
 868        if (IS_ERR(sock))
 869                fput(file);
 870        return sock;
 871}
 872
 873static struct socket *get_socket(int fd)
 874{
 875        struct socket *sock;
 876
 877        /* special case to disable backend */
 878        if (fd == -1)
 879                return NULL;
 880        sock = get_raw_socket(fd);
 881        if (!IS_ERR(sock))
 882                return sock;
 883        sock = get_tap_socket(fd);
 884        if (!IS_ERR(sock))
 885                return sock;
 886        return ERR_PTR(-ENOTSOCK);
 887}
 888
 889static long vhost_net_set_backend(struct vhost_net *n, unsigned index, int fd)
 890{
 891        struct socket *sock, *oldsock;
 892        struct vhost_virtqueue *vq;
 893        struct vhost_net_virtqueue *nvq;
 894        struct vhost_net_ubuf_ref *ubufs, *oldubufs = NULL;
 895        int r;
 896
 897        mutex_lock(&n->dev.mutex);
 898        r = vhost_dev_check_owner(&n->dev);
 899        if (r)
 900                goto err;
 901
 902        if (index >= VHOST_NET_VQ_MAX) {
 903                r = -ENOBUFS;
 904                goto err;
 905        }
 906        vq = &n->vqs[index].vq;
 907        nvq = &n->vqs[index];
 908        mutex_lock(&vq->mutex);
 909
 910        /* Verify that ring has been setup correctly. */
 911        if (!vhost_vq_access_ok(vq)) {
 912                r = -EFAULT;
 913                goto err_vq;
 914        }
 915        sock = get_socket(fd);
 916        if (IS_ERR(sock)) {
 917                r = PTR_ERR(sock);
 918                goto err_vq;
 919        }
 920
 921        /* start polling new socket */
 922        oldsock = vq->private_data;
 923        if (sock != oldsock) {
 924                ubufs = vhost_net_ubuf_alloc(vq,
 925                                             sock && vhost_sock_zcopy(sock));
 926                if (IS_ERR(ubufs)) {
 927                        r = PTR_ERR(ubufs);
 928                        goto err_ubufs;
 929                }
 930
 931                vhost_net_disable_vq(n, vq);
 932                vq->private_data = sock;
 933                r = vhost_init_used(vq);
 934                if (r)
 935                        goto err_used;
 936                r = vhost_net_enable_vq(n, vq);
 937                if (r)
 938                        goto err_used;
 939
 940                oldubufs = nvq->ubufs;
 941                nvq->ubufs = ubufs;
 942
 943                n->tx_packets = 0;
 944                n->tx_zcopy_err = 0;
 945                n->tx_flush = false;
 946        }
 947
 948        mutex_unlock(&vq->mutex);
 949
 950        if (oldubufs) {
 951                vhost_net_ubuf_put_wait_and_free(oldubufs);
 952                mutex_lock(&vq->mutex);
 953                vhost_zerocopy_signal_used(n, vq);
 954                mutex_unlock(&vq->mutex);
 955        }
 956
 957        if (oldsock) {
 958                vhost_net_flush_vq(n, index);
 959                fput(oldsock->file);
 960        }
 961
 962        mutex_unlock(&n->dev.mutex);
 963        return 0;
 964
 965err_used:
 966        vq->private_data = oldsock;
 967        vhost_net_enable_vq(n, vq);
 968        if (ubufs)
 969                vhost_net_ubuf_put_wait_and_free(ubufs);
 970err_ubufs:
 971        fput(sock->file);
 972err_vq:
 973        mutex_unlock(&vq->mutex);
 974err:
 975        mutex_unlock(&n->dev.mutex);
 976        return r;
 977}
 978
 979static long vhost_net_reset_owner(struct vhost_net *n)
 980{
 981        struct socket *tx_sock = NULL;
 982        struct socket *rx_sock = NULL;
 983        long err;
 984        struct vhost_memory *memory;
 985
 986        mutex_lock(&n->dev.mutex);
 987        err = vhost_dev_check_owner(&n->dev);
 988        if (err)
 989                goto done;
 990        memory = vhost_dev_reset_owner_prepare();
 991        if (!memory) {
 992                err = -ENOMEM;
 993                goto done;
 994        }
 995        vhost_net_stop(n, &tx_sock, &rx_sock);
 996        vhost_net_flush(n);
 997        vhost_dev_reset_owner(&n->dev, memory);
 998        vhost_net_vq_reset(n);
 999done:
1000        mutex_unlock(&n->dev.mutex);
1001        if (tx_sock)
1002                fput(tx_sock->file);
1003        if (rx_sock)
1004                fput(rx_sock->file);
1005        return err;
1006}
1007
1008static int vhost_net_set_features(struct vhost_net *n, u64 features)
1009{
1010        size_t vhost_hlen, sock_hlen, hdr_len;
1011        int i;
1012
1013        hdr_len = (features & (1 << VIRTIO_NET_F_MRG_RXBUF)) ?
1014                        sizeof(struct virtio_net_hdr_mrg_rxbuf) :
1015                        sizeof(struct virtio_net_hdr);
1016        if (features & (1 << VHOST_NET_F_VIRTIO_NET_HDR)) {
1017                /* vhost provides vnet_hdr */
1018                vhost_hlen = hdr_len;
1019                sock_hlen = 0;
1020        } else {
1021                /* socket provides vnet_hdr */
1022                vhost_hlen = 0;
1023                sock_hlen = hdr_len;
1024        }
1025        mutex_lock(&n->dev.mutex);
1026        if ((features & (1 << VHOST_F_LOG_ALL)) &&
1027            !vhost_log_access_ok(&n->dev)) {
1028                mutex_unlock(&n->dev.mutex);
1029                return -EFAULT;
1030        }
1031        n->dev.acked_features = features;
1032        smp_wmb();
1033        for (i = 0; i < VHOST_NET_VQ_MAX; ++i) {
1034                mutex_lock(&n->vqs[i].vq.mutex);
1035                n->vqs[i].vhost_hlen = vhost_hlen;
1036                n->vqs[i].sock_hlen = sock_hlen;
1037                mutex_unlock(&n->vqs[i].vq.mutex);
1038        }
1039        vhost_net_flush(n);
1040        mutex_unlock(&n->dev.mutex);
1041        return 0;
1042}
1043
1044static long vhost_net_set_owner(struct vhost_net *n)
1045{
1046        int r;
1047
1048        mutex_lock(&n->dev.mutex);
1049        if (vhost_dev_has_owner(&n->dev)) {
1050                r = -EBUSY;
1051                goto out;
1052        }
1053        r = vhost_net_set_ubuf_info(n);
1054        if (r)
1055                goto out;
1056        r = vhost_dev_set_owner(&n->dev);
1057        if (r)
1058                vhost_net_clear_ubuf_info(n);
1059        vhost_net_flush(n);
1060out:
1061        mutex_unlock(&n->dev.mutex);
1062        return r;
1063}
1064
1065static long vhost_net_ioctl(struct file *f, unsigned int ioctl,
1066                            unsigned long arg)
1067{
1068        struct vhost_net *n = f->private_data;
1069        void __user *argp = (void __user *)arg;
1070        u64 __user *featurep = argp;
1071        struct vhost_vring_file backend;
1072        u64 features;
1073        int r;
1074
1075        switch (ioctl) {
1076        case VHOST_NET_SET_BACKEND:
1077                if (copy_from_user(&backend, argp, sizeof backend))
1078                        return -EFAULT;
1079                return vhost_net_set_backend(n, backend.index, backend.fd);
1080        case VHOST_GET_FEATURES:
1081                features = VHOST_NET_FEATURES;
1082                if (copy_to_user(featurep, &features, sizeof features))
1083                        return -EFAULT;
1084                return 0;
1085        case VHOST_SET_FEATURES:
1086                if (copy_from_user(&features, featurep, sizeof features))
1087                        return -EFAULT;
1088                if (features & ~VHOST_NET_FEATURES)
1089                        return -EOPNOTSUPP;
1090                return vhost_net_set_features(n, features);
1091        case VHOST_RESET_OWNER:
1092                return vhost_net_reset_owner(n);
1093        case VHOST_SET_OWNER:
1094                return vhost_net_set_owner(n);
1095        default:
1096                mutex_lock(&n->dev.mutex);
1097                r = vhost_dev_ioctl(&n->dev, ioctl, argp);
1098                if (r == -ENOIOCTLCMD)
1099                        r = vhost_vring_ioctl(&n->dev, ioctl, argp);
1100                else
1101                        vhost_net_flush(n);
1102                mutex_unlock(&n->dev.mutex);
1103                return r;
1104        }
1105}
1106
1107#ifdef CONFIG_COMPAT
1108static long vhost_net_compat_ioctl(struct file *f, unsigned int ioctl,
1109                                   unsigned long arg)
1110{
1111        return vhost_net_ioctl(f, ioctl, (unsigned long)compat_ptr(arg));
1112}
1113#endif
1114
1115static const struct file_operations vhost_net_fops = {
1116        .owner          = THIS_MODULE,
1117        .release        = vhost_net_release,
1118        .unlocked_ioctl = vhost_net_ioctl,
1119#ifdef CONFIG_COMPAT
1120        .compat_ioctl   = vhost_net_compat_ioctl,
1121#endif
1122        .open           = vhost_net_open,
1123        .llseek         = noop_llseek,
1124};
1125
1126static struct miscdevice vhost_net_misc = {
1127        .minor = VHOST_NET_MINOR,
1128        .name = "vhost-net",
1129        .fops = &vhost_net_fops,
1130};
1131
1132static int vhost_net_init(void)
1133{
1134        if (experimental_zcopytx)
1135                vhost_net_enable_zcopy(VHOST_NET_VQ_TX);
1136        return misc_register(&vhost_net_misc);
1137}
1138module_init(vhost_net_init);
1139
1140static void vhost_net_exit(void)
1141{
1142        misc_deregister(&vhost_net_misc);
1143}
1144module_exit(vhost_net_exit);
1145
1146MODULE_VERSION("0.0.1");
1147MODULE_LICENSE("GPL v2");
1148MODULE_AUTHOR("Michael S. Tsirkin");
1149MODULE_DESCRIPTION("Host kernel accelerator for virtio net");
1150MODULE_ALIAS_MISCDEV(VHOST_NET_MINOR);
1151MODULE_ALIAS("devname:vhost-net");
1152
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